Linear–nonlinear models of the red–green chromatic pathway

Stockman, Andrew; Henning, G. Bruce; Rider, Andrew T.

doi:10.1167/17.13.7

Cited by 5 publications

(15 citation statements)

References 51 publications

(75 reference statements)

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“…Moreover, the ''chromatic'' parvocellular response may correspond to responses of single cones and their surrounds feeding back into the network. The nonlinearity that produces the second harmonic is likely to correspond to the half-wave rectification and partition of the photoreceptor signal into ON and OFF pathways that also occurs in the outer retina (see also Stockman, Henning, & Rider, 2017).…”

Section: Magnocellular Ganglion Cellsmentioning

confidence: 99%

Delayed cone-opponent signals in the luminance pathway

et al. 2018

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Cone signals in the luminance or achromatic pathway were investigated by measuring how the perceptual timing of M- or L-cone-detected flicker depended on temporal frequency and chromatic adaptation. Relative timings were measured, as a function of temporal frequency, by superimposing M- or L-cone-isolating flicker on "equichromatic" flicker (flicker of the same wavelength as the background) and asking observers to vary contrast and phase to cancel the perception of flicker. Measurements were made in four observers on up to 35 different backgrounds varying in wavelength and radiance. Observers showed substantial perceptual delays or advances of L- and M-cone flicker that varied systematically with cone class, background wavelength, and radiance. Delays were largest for M-cone-isolating flicker. Although complex, the results can be characterised by a surprisingly simple model in which the representations of L- and M-cone flicker are comprised not only of a fast copy of the flicker signal, but also of a slow copy that is delayed by roughly 30 ms and varies in strength and sign with both background wavelength and radiance. The delays, which are too large to be due to selective cone adaptation by the chromatic backgrounds, must arise postreceptorally. Clear evidence for the slow signals can also be found in physiological measurements of horizontal and magnocellular ganglion cells, thus placing the origin of the slow signals in the retina-most likely in an extended horizontal cell network. Luminance-equated stimuli chosen to isolate chromatic channels may inadvertently generate slow signals in the luminance channel.

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Section: Magnocellular Ganglion Cellsmentioning

confidence: 99%

Delayed cone-opponent signals in the luminance pathway

et al. 2018

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“…The amplitude ratios for the other three combinations were predicted by our model ( 22 ) to produce large color shifts. The two-component stimuli ( i and ii ) were used, because they provide useful information about relative phase changes produced by the early filter in our model (to be discussed below); the results can be used to constrain the parameters of that filter ( 22 ). Combination iii (the first, third, and fourth harmonics) was chosen to examine the effect of high-frequency components—as we note below, the crucial component here is the fourth harmonic.…”

Section: Resultsmentioning

confidence: 63%

Section: Resultsmentioning

confidence: 99%

“…The amplitude ratio used in i was chosen to be consistent with our previous work ( 22 ), being the ratio of first and second harmonic components of the sawtooth waveforms used in that work. The amplitude ratios for the other three combinations were predicted by our model ( 22 ) to produce large color shifts. The two-component stimuli ( i and ii ) were used, because they provide useful information about relative phase changes produced by the early filter in our model (to be discussed below); the results can be used to constrain the parameters of that filter ( 22 ).…”

Section: Resultsmentioning

confidence: 99%

“…By contrast, a change in the mean output (and thus, in mean appearance) would be expected if the stimuli are not half-wave symmetric, because the positive and negative parts of the asymmetrical stimuli will be unequally affected by matching nonlinearities in the ON and OFF pathways. Examples of changes in mean appearance found for such stimuli include the illusory change in mean brightness produced by the eye moving across a black and white sawtooth pattern ( 19 ) and the illusory changes in mean color when red and green lights are flickered around the mean using asymmetrical patterns ( 20 – 22 ).…”

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Harmonics added to a flickering light can upset the balance between ON and OFF pathways to produce illusory colors

Rider¹,

Henning²,

Eskew³

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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SignificanceBy varying the temporal waveforms of complex flickering stimuli, we can produce alterations in their mean color that can be predicted by a physiologically based model of visual processing. The model highlights the perceptual effects of a well-known feature of most visual pathways, namely the early separation of visual signals into increments and decrements. The role of this separation in improving the efficiency and sensitivity of the visual system has been discussed before, but its effect on perception has been neglected. The application of a model incorporating half-wave rectification offers an exciting psychophysical method for investigating the inner workings of the human visual system.

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Tuning of cortical color mechanism revealed using steady-state visually evoked potentials

Watts,

Rozman,

Somers

et al. 2023

Preprint

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Color information is thought to be received by the primary visual cortex via two dominant retinogeniculate pathways, one signals color variation between teal and red, and the other signals color variation between violet and lime. This representation is thought to be transformed in the cortex so that there are a number of different cell populations representing a greater variety of hues. However, the properties of cortical color mechanisms are not well understood. In four experiments, we characterized the tuning functions of cortical color mechanisms by measuring the intermodulation of steady-state visually evoked potentials (SSVEPs). Stimuli were isoluminant chromatic checkerboards where odd and even checks flickered at different frequencies. As hue dissimilarity between the odd and even checks increased, the amplitude of an intermodulation component (I1) at the sum of the two stimulus frequencies decreased, revealing cortical color tuning functions. In Experiment 1 we found similar broad tuning functions for ‘cardinal’ and intermediate color axes, implying that the cortex has intermediately tuned color mechanisms. In Experiment 2 we found similar broad tuning functions for ‘checkerboards’ with no perceptible edges because the checks were formed from single pixels (∼0.096°), implying that the underlying neural populations do not rely on spatial chromatic edges. In Experiment 3 we manipulated check size and found that color tuning functions were consistent across check sizes used. In Experiment 4 we measured full 360° tuning functions for a ‘cardinal’ cortical color mechanism and found evidence for opponent (bipolar) color responses. The observed cortical color tuning functions were consistent with those measured using psychophysics and electrophysiology, implying that tracking intermodulation using SSVEPs provides a useful method for measuring them.

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Linear–nonlinear models of the red–green chromatic pathway

Cited by 5 publications

References 51 publications

Delayed cone-opponent signals in the luminance pathway

Delayed cone-opponent signals in the luminance pathway

Harmonics added to a flickering light can upset the balance between ON and OFF pathways to produce illusory colors

Tuning of cortical color mechanism revealed using steady-state visually evoked potentials

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